My 2 cents on the save game issue,
After installation of Chapter 2 in area's with activity, like Sanctuary, standing in front of the bridge towards Red Rocket the game would freeze as soon I tried to save.
In area's with no activity for example inside a building, game would save and go back to the menu after a waiting period.
So I started to experiment a bit, till I became at a point that I removed the usb gamepad connection during a save. When I did that, the game saved immediately and going back to the menu like always. I then went ahead shut down the game and unplugged my phone as well. After a restart I plugged them both in again, fired up the game and continued. Since that moment I have no save game issues anymore. It saves just as fast as it did before on my system.
The result might be influenced because I also disabled / enabled the mod RAW Input & Raw Input stuttering fix. I am still using the mod Autoswitch, to switch from Gamepad to keyboard / mouse on the fly. In Buffout 4 I have the switch tweak set to false.
Sorry I can't provide a log or something, I didn't expect this outcome, thought I would share it anyway. I did all this on Hotfix 2.0.0d.